#include "common.h"

#define RRD_TYPE_DISK "disk"

#define DISK_TYPE_PHYSICAL  1
#define DISK_TYPE_PARTITION 2
#define DISK_TYPE_CONTAINER 3

#ifndef NETDATA_RELOAD_MOUNTINFO_EVERY
#define NETDATA_RELOAD_MOUNTINFO_EVERY 10
#endif

static struct disk {
    char *disk;             // the name of the disk (sda, sdb, etc)
    unsigned long major;
    unsigned long minor;
    int sector_size;
    int type;

    char *mount_point;

    // disk options caching
    int configured;
    int do_io;
    int do_ops;
    int do_mops;
    int do_iotime;
    int do_qops;
    int do_util;
    int do_backlog;

    struct disk *next;
} *disk_root = NULL;

static struct mountinfo *disk_mountinfo_root = NULL;

static inline void mountinfo_reload(int force) {
    static time_t last_loaded = 0;
    time_t now = now_realtime_sec();

    if(force || now - last_loaded >= NETDATA_RELOAD_MOUNTINFO_EVERY) {
//#ifdef NETDATA_INTERNAL_CHECKS
//        info("Reloading mountinfo");
//#endif

        // mountinfo_free() can be called with NULL disk_mountinfo_root
        mountinfo_free(disk_mountinfo_root);

        // re-read mountinfo in case something changed
        disk_mountinfo_root = mountinfo_read();

        last_loaded = now;
    }
}


// linked list of mount points that are by default disabled
static struct excluded_mount_point {
    const char *prefix;
    size_t len;
    struct excluded_mount_point *next;
} *excluded_mount_points = NULL;

static inline int is_mount_point_excluded(const char *mount_point) {
    static int initialized = 0;

    if(unlikely(!initialized)) {
        initialized = 1;

        char *a = config_get("plugin:proc:/proc/diskstats", "exclude space metrics on paths", "/proc/ /sys/ /var/run/user/ /run/user/");
        if(a && *a) {
            char *s = a;

            while(s && *s) {
                // skip all spaces
                while(isspace(*s)) s++;

                // empty string
                if(unlikely(!*s)) break;

                // find the next space
                char *c = s;
                while(*c && !isspace(*c)) c++;

                char *n;
                if(likely(*c)) n = c + 1;
                else n = NULL;

                // terminate our string
                *c = '\0';

                // allocate the structure
                struct excluded_mount_point *m = mallocz(sizeof(struct excluded_mount_point));
                m->prefix = strdup(s);
                m->len = strlen(m->prefix);
                m->next = excluded_mount_points;
                excluded_mount_points = m;

                // prepare for next loop
                s = n;
                if(likely(n)) *c = ' ';
            }
        }
    }

    size_t len = strlen(mount_point);
    struct excluded_mount_point *m;
    for(m = excluded_mount_points; m ; m = m->next) {
        if(m->len <= len) {
            // fprintf(stderr, "SPACE: comparing '%s' with '%s'\n", mount_point, m->prefix);
            if(unlikely(strncmp(m->prefix, mount_point, m->len) == 0)) {
                // fprintf(stderr, "SPACE: excluded '%s'\n", mount_point);
                return 1;
            }
        }
    }

    // fprintf(stderr, "SPACE: included '%s'\n", mount_point);
    return 0;
}

// Data to be stored in DICTIONARY mount_points used by do_disk_space_stats().
// This DICTIONARY is used to lookup the settings of the mount point on each iteration.
struct mount_point_metadata {
    int do_space;
    int do_inodes;
};

static inline void do_disk_space_stats(struct mountinfo *mi, int update_every, usec_t dt) {
    (void)dt;

    const char *family = mi->mount_point;
    const char *disk = mi->persistent_id;

    static DICTIONARY *mount_points = NULL;
    int do_space, do_inodes;

    if(unlikely(!mount_points)) {
        mount_points = dictionary_create(DICTIONARY_FLAG_SINGLE_THREADED);
    }

    struct mount_point_metadata *m = dictionary_get(mount_points, mi->mount_point);
    if(unlikely(!m)) {
        char var_name[4096 + 1];
        snprintfz(var_name, 4096, "plugin:proc:/proc/diskstats:%s", mi->mount_point);

        int def_space = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "space usage for all disks", CONFIG_ONDEMAND_ONDEMAND);
        int def_inodes = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "inodes usage for all disks", CONFIG_ONDEMAND_ONDEMAND);

        if(unlikely(is_mount_point_excluded(mi->mount_point))) {
            def_space = CONFIG_ONDEMAND_NO;
            def_inodes = CONFIG_ONDEMAND_NO;
        }

        do_space = config_get_boolean_ondemand(var_name, "space usage", def_space);
        do_inodes = config_get_boolean_ondemand(var_name, "inodes usage", def_inodes);

        struct mount_point_metadata mp = {
            .do_space = do_space,
            .do_inodes = do_inodes
        };

        dictionary_set(mount_points, mi->mount_point, &mp, sizeof(struct mount_point_metadata));
    }
    else {
        do_space = m->do_space;
        do_inodes = m->do_inodes;
    }

    if(unlikely(do_space == CONFIG_ONDEMAND_NO && do_inodes == CONFIG_ONDEMAND_NO))
        return;

    struct statvfs buff_statvfs;
    if (statvfs(mi->mount_point, &buff_statvfs) < 0) {
        error("Failed statvfs() for '%s' (disk '%s')", mi->mount_point, disk);
        return;
    }

    // taken from get_fs_usage() found in coreutils
    unsigned long bsize = (buff_statvfs.f_frsize) ? buff_statvfs.f_frsize : buff_statvfs.f_bsize;

    fsblkcnt_t bavail         = buff_statvfs.f_bavail;
    fsblkcnt_t btotal         = buff_statvfs.f_blocks;
    fsblkcnt_t bavail_root    = buff_statvfs.f_bfree;
    fsblkcnt_t breserved_root = bavail_root - bavail;
    fsblkcnt_t bused;
    if(likely(btotal >= bavail_root))
        bused = btotal - bavail_root;
    else
        bused = bavail_root - btotal;

#ifdef NETDATA_INTERNAL_CHECKS
    if(unlikely(btotal != bavail + breserved_root + bused))
        error("Disk block statistics for '%s' (disk '%s') do not sum up: total = %llu, available = %llu, reserved = %llu, used = %llu", mi->mount_point, disk, (unsigned long long)btotal, (unsigned long long)bavail, (unsigned long long)breserved_root, (unsigned long long)bused);
#endif

    // --------------------------------------------------------------------------

    fsfilcnt_t favail         = buff_statvfs.f_favail;
    fsfilcnt_t ftotal         = buff_statvfs.f_files;
    fsfilcnt_t favail_root    = buff_statvfs.f_ffree;
    fsfilcnt_t freserved_root = favail_root - favail;
    fsfilcnt_t fused          = ftotal - favail_root;

#ifdef NETDATA_INTERNAL_CHECKS
    if(unlikely(btotal != bavail + breserved_root + bused))
        error("Disk inode statistics for '%s' (disk '%s') do not sum up: total = %llu, available = %llu, reserved = %llu, used = %llu", mi->mount_point, disk, (unsigned long long)ftotal, (unsigned long long)favail, (unsigned long long)freserved_root, (unsigned long long)fused);
#endif

    // --------------------------------------------------------------------------

    RRDSET *st;

    if(do_space == CONFIG_ONDEMAND_YES || (do_space == CONFIG_ONDEMAND_ONDEMAND && (bavail || breserved_root || bused))) {
        st = rrdset_find_bytype("disk_space", disk);
        if(unlikely(!st)) {
            char title[4096 + 1];
            snprintfz(title, 4096, "Disk Space Usage for %s [%s]", family, mi->mount_source);
            st = rrdset_create("disk_space", disk, NULL, family, "disk.space", title, "GB", 2023, update_every, RRDSET_TYPE_STACKED);

            rrddim_add(st, "avail", NULL, bsize, 1024*1024*1024, RRDDIM_ABSOLUTE);
            rrddim_add(st, "used" , NULL, bsize, 1024*1024*1024, RRDDIM_ABSOLUTE);
            rrddim_add(st, "reserved_for_root", "reserved for root", bsize, 1024*1024*1024, RRDDIM_ABSOLUTE);
        }
        else rrdset_next(st);

        rrddim_set(st, "avail", (collected_number)bavail);
        rrddim_set(st, "used", (collected_number)bused);
        rrddim_set(st, "reserved_for_root", (collected_number)breserved_root);
        rrdset_done(st);
    }

    // --------------------------------------------------------------------------

    if(do_inodes == CONFIG_ONDEMAND_YES || (do_inodes == CONFIG_ONDEMAND_ONDEMAND && (favail || freserved_root || fused))) {
        st = rrdset_find_bytype("disk_inodes", disk);
        if(unlikely(!st)) {
            char title[4096 + 1];
            snprintfz(title, 4096, "Disk Files (inodes) Usage for %s [%s]", family, mi->mount_source);
            st = rrdset_create("disk_inodes", disk, NULL, family, "disk.inodes", title, "Inodes", 2024, update_every, RRDSET_TYPE_STACKED);

            rrddim_add(st, "avail", NULL, 1, 1, RRDDIM_ABSOLUTE);
            rrddim_add(st, "used" , NULL, 1, 1, RRDDIM_ABSOLUTE);
            rrddim_add(st, "reserved_for_root", "reserved for root", 1, 1, RRDDIM_ABSOLUTE);
        }
        else rrdset_next(st);

        rrddim_set(st, "avail", (collected_number)favail);
        rrddim_set(st, "used", (collected_number)fused);
        rrddim_set(st, "reserved_for_root", (collected_number)freserved_root);
        rrdset_done(st);
    }
}

static struct disk *get_disk(unsigned long major, unsigned long minor, char *disk) {
    static char path_to_get_hw_sector_size[FILENAME_MAX + 1] = "";
    static char path_to_get_hw_sector_size_partitions[FILENAME_MAX + 1] = "";
    static char path_find_block_device[FILENAME_MAX + 1] = "";
    struct disk *d;

    // search for it in our RAM list.
    // this is sequential, but since we just walk through
    // and the number of disks / partitions in a system
    // should not be that many, it should be acceptable
    for(d = disk_root; d ; d = d->next)
        if(unlikely(d->major == major && d->minor == minor))
            break;

    // if we found it, return it
    if(likely(d))
        return d;

    // not found
    // create a new disk structure
    d = (struct disk *)mallocz(sizeof(struct disk));

    d->disk = strdupz(disk);
    d->major = major;
    d->minor = minor;
    d->type = DISK_TYPE_PHYSICAL; // Default type. Changed later if not correct.
    d->configured = 0;
    d->sector_size = 512; // the default, will be changed below
    d->next = NULL;

    // append it to the list
    if(unlikely(!disk_root))
        disk_root = d;
    else {
        struct disk *last;
        for(last = disk_root; last->next ;last = last->next);
        last->next = d;
    }

    // ------------------------------------------------------------------------
    // find the type of the device

    char buffer[FILENAME_MAX + 1];

    // get the default path for finding info about the block device
    if(unlikely(!path_find_block_device[0])) {
        snprintfz(buffer, FILENAME_MAX, "%s%s", global_host_prefix, "/sys/dev/block/%lu:%lu/%s");
        snprintfz(path_find_block_device, FILENAME_MAX, "%s", config_get("plugin:proc:/proc/diskstats", "path to get block device infos", buffer));
    }

    // find if it is a partition
    // by checking if /sys/dev/block/MAJOR:MINOR/partition is readable.
    snprintfz(buffer, FILENAME_MAX, path_find_block_device, major, minor, "partition");
    if(likely(access(buffer, R_OK) == 0)) {
        d->type = DISK_TYPE_PARTITION;
    }
    else {
        // find if it is a container
        // by checking if /sys/dev/block/MAJOR:MINOR/slaves has entries
        snprintfz(buffer, FILENAME_MAX, path_find_block_device, major, minor, "slaves/");
        DIR *dirp = opendir(buffer);
        if(likely(dirp != NULL)) {
            struct dirent *dp;
            while( (dp = readdir(dirp)) ) {
                // . and .. are also files in empty folders.
                if(unlikely(strcmp(dp->d_name, ".") == 0 || strcmp(dp->d_name, "..") == 0)) {
                    continue;
                }

                d->type = DISK_TYPE_CONTAINER;

                // Stop the loop after we found one file.
                break;
            }
            if(unlikely(closedir(dirp) == -1))
                error("Unable to close dir %s", buffer);
        }
    }

    // ------------------------------------------------------------------------
    // check if we can find its mount point

    // mountinfo_find() can be called with NULL disk_mountinfo_root
    struct mountinfo *mi = mountinfo_find(disk_mountinfo_root, d->major, d->minor);
    if(unlikely(mi))
        d->mount_point = strdupz(mi->mount_point);
    else
        d->mount_point = NULL;

    // ------------------------------------------------------------------------
    // find the disk sector size

    if(unlikely(!path_to_get_hw_sector_size[0])) {
        snprintfz(buffer, FILENAME_MAX, "%s%s", global_host_prefix, "/sys/block/%s/queue/hw_sector_size");
        snprintfz(path_to_get_hw_sector_size, FILENAME_MAX, "%s", config_get("plugin:proc:/proc/diskstats", "path to get h/w sector size", buffer));
    }
    if(unlikely(!path_to_get_hw_sector_size_partitions[0])) {
        snprintfz(buffer, FILENAME_MAX, "%s%s", global_host_prefix, "/sys/dev/block/%lu:%lu/subsystem/%s/../queue/hw_sector_size");
        snprintfz(path_to_get_hw_sector_size_partitions, FILENAME_MAX, "%s", config_get("plugin:proc:/proc/diskstats", "path to get h/w sector size for partitions", buffer));
    }

    {
        char tf[FILENAME_MAX + 1], *t;
        strncpyz(tf, d->disk, FILENAME_MAX);

        // replace all / with !
        for(t = tf; *t ;t++)
            if(unlikely(*t == '/')) *t = '!';

        if(likely(d->type == DISK_TYPE_PARTITION))
            snprintfz(buffer, FILENAME_MAX, path_to_get_hw_sector_size_partitions, d->major, d->minor, tf);
        else
            snprintfz(buffer, FILENAME_MAX, path_to_get_hw_sector_size, tf);

        FILE *fpss = fopen(buffer, "r");
        if(likely(fpss)) {
            char buffer2[1024 + 1];
            char *tmp = fgets(buffer2, 1024, fpss);

            if(likely(tmp)) {
                d->sector_size = atoi(tmp);
                if(unlikely(d->sector_size <= 0)) {
                    error("Invalid sector size %d for device %s in %s. Assuming 512.", d->sector_size, d->disk, buffer);
                    d->sector_size = 512;
                }
            }
            else error("Cannot read data for sector size for device %s from %s. Assuming 512.", d->disk, buffer);

            fclose(fpss);
        }
        else error("Cannot read sector size for device %s from %s. Assuming 512.", d->disk, buffer);
    }

    return d;
}

static inline int select_positive_option(int option1, int option2) {
    if(unlikely(option1 == CONFIG_ONDEMAND_YES || option2 == CONFIG_ONDEMAND_YES))
        return CONFIG_ONDEMAND_YES;
    else if(unlikely(option1 == CONFIG_ONDEMAND_ONDEMAND || option2 == CONFIG_ONDEMAND_ONDEMAND))
        return CONFIG_ONDEMAND_ONDEMAND;

    return CONFIG_ONDEMAND_NO;
}

static inline int is_major_enabled(int major) {
    static char *major_configs = NULL;
    static size_t major_size = 0;

    if(major < 0) return 1;

    size_t wanted_size = (size_t)major + 1;

    if(major_size < wanted_size) {
        major_configs = reallocz(major_configs, wanted_size);

        size_t i;
        for(i = major_size; i < wanted_size ; i++)
            major_configs[i] = -1;

        major_size = wanted_size;
    }

    if(major_configs[major] == -1) {
        char buffer[CONFIG_MAX_NAME + 1];
        snprintfz(buffer, CONFIG_MAX_NAME, "performance metrics for disks with major %d", major);
        major_configs[major] = (char)config_get_boolean("plugin:proc:/proc/diskstats", buffer, 1);
    }

    return major_configs[major];
}

int do_proc_diskstats(int update_every, usec_t dt) {
    (void)dt;

    static procfile *ff = NULL;
    static int  global_enable_new_disks_detected_at_runtime = CONFIG_ONDEMAND_YES,
                global_enable_performance_for_physical_disks = CONFIG_ONDEMAND_ONDEMAND,
                global_enable_performance_for_virtual_disks = CONFIG_ONDEMAND_ONDEMAND,
                global_enable_performance_for_partitions = CONFIG_ONDEMAND_NO,
                global_do_io = CONFIG_ONDEMAND_ONDEMAND,
                global_do_ops = CONFIG_ONDEMAND_ONDEMAND,
                global_do_mops = CONFIG_ONDEMAND_ONDEMAND,
                global_do_iotime = CONFIG_ONDEMAND_ONDEMAND,
                global_do_qops = CONFIG_ONDEMAND_ONDEMAND,
                global_do_util = CONFIG_ONDEMAND_ONDEMAND,
                global_do_backlog = CONFIG_ONDEMAND_ONDEMAND,
                globals_initialized = 0;

    if(unlikely(!globals_initialized)) {
        global_enable_new_disks_detected_at_runtime = config_get_boolean("plugin:proc:/proc/diskstats", "enable new disks detected at runtime", global_enable_new_disks_detected_at_runtime);

        global_enable_performance_for_physical_disks = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "performance metrics for physical disks", global_enable_performance_for_physical_disks);
        global_enable_performance_for_virtual_disks = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "performance metrics for virtual disks", global_enable_performance_for_virtual_disks);
        global_enable_performance_for_partitions = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "performance metrics for partitions", global_enable_performance_for_partitions);

        global_do_io      = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "bandwidth for all disks", global_do_io);
        global_do_ops     = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "operations for all disks", global_do_ops);
        global_do_mops    = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "merged operations for all disks", global_do_mops);
        global_do_iotime  = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "i/o time for all disks", global_do_iotime);
        global_do_qops    = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "queued operations for all disks", global_do_qops);
        global_do_util    = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "utilization percentage for all disks", global_do_util);
        global_do_backlog = config_get_boolean_ondemand("plugin:proc:/proc/diskstats", "backlog for all disks", global_do_backlog);

        globals_initialized = 1;
    }

    // --------------------------------------------------------------------------
    // this is smart enough not to reload it every time

    mountinfo_reload(0);

    // --------------------------------------------------------------------------
    // disk space metrics

    struct mountinfo *mi;
    for(mi = disk_mountinfo_root; mi ;mi = mi->next) {
        if(unlikely(mi->flags & (MOUNTINFO_IS_DUMMY|MOUNTINFO_IS_BIND|MOUNTINFO_IS_SAME_DEV|MOUNTINFO_NO_STAT|MOUNTINFO_NO_SIZE|MOUNTINFO_READONLY)))
            continue;

        do_disk_space_stats(mi, update_every, dt);
    }

    // --------------------------------------------------------------------------

    if(unlikely(!ff)) {
        char filename[FILENAME_MAX + 1];
        snprintfz(filename, FILENAME_MAX, "%s%s", global_host_prefix, "/proc/diskstats");
        ff = procfile_open(config_get("plugin:proc:/proc/diskstats", "filename to monitor", filename), " \t", PROCFILE_FLAG_DEFAULT);
    }
    if(unlikely(!ff)) return 0;

    ff = procfile_readall(ff);
    if(unlikely(!ff)) return 0; // we return 0, so that we will retry to open it next time

    uint32_t lines = procfile_lines(ff), l;

    for(l = 0; l < lines ;l++) {
        // --------------------------------------------------------------------------
        // Read parameters

        char *disk;
        unsigned long       major = 0, minor = 0;

        collected_number    reads = 0,  mreads = 0,  readsectors = 0,  readms = 0,
                            writes = 0, mwrites = 0, writesectors = 0, writems = 0,
                            queued_ios = 0, busy_ms = 0, backlog_ms = 0;

        collected_number    last_reads = 0,  last_readsectors = 0,  last_readms = 0,
                            last_writes = 0, last_writesectors = 0, last_writems = 0,
                            last_busy_ms = 0;

        uint32_t words = procfile_linewords(ff, l);
        if(unlikely(words < 14)) continue;

        major           = strtoul(procfile_lineword(ff, l, 0), NULL, 10);
        minor           = strtoul(procfile_lineword(ff, l, 1), NULL, 10);
        disk            = procfile_lineword(ff, l, 2);

        // # of reads completed # of writes completed
        // This is the total number of reads or writes completed successfully.
        reads           = strtoull(procfile_lineword(ff, l, 3), NULL, 10);  // rd_ios
        writes          = strtoull(procfile_lineword(ff, l, 7), NULL, 10);  // wr_ios

        // # of reads merged # of writes merged
        // Reads and writes which are adjacent to each other may be merged for
        // efficiency.  Thus two 4K reads may become one 8K read before it is
        // ultimately handed to the disk, and so it will be counted (and queued)
        mreads          = strtoull(procfile_lineword(ff, l, 4), NULL, 10);  // rd_merges_or_rd_sec
        mwrites         = strtoull(procfile_lineword(ff, l, 8), NULL, 10);  // wr_merges

        // # of sectors read # of sectors written
        // This is the total number of sectors read or written successfully.
        readsectors     = strtoull(procfile_lineword(ff, l, 5), NULL, 10);  // rd_sec_or_wr_ios
        writesectors    = strtoull(procfile_lineword(ff, l, 9), NULL, 10);  // wr_sec

        // # of milliseconds spent reading # of milliseconds spent writing
        // This is the total number of milliseconds spent by all reads or writes (as
        // measured from __make_request() to end_that_request_last()).
        readms          = strtoull(procfile_lineword(ff, l, 6), NULL, 10);  // rd_ticks_or_wr_sec
        writems         = strtoull(procfile_lineword(ff, l, 10), NULL, 10); // wr_ticks

        // # of I/Os currently in progress
        // The only field that should go to zero. Incremented as requests are
        // given to appropriate struct request_queue and decremented as they finish.
        queued_ios      = strtoull(procfile_lineword(ff, l, 11), NULL, 10); // ios_pgr

        // # of milliseconds spent doing I/Os
        // This field increases so long as field queued_ios is nonzero.
        busy_ms         = strtoull(procfile_lineword(ff, l, 12), NULL, 10); // tot_ticks

        // weighted # of milliseconds spent doing I/Os
        // This field is incremented at each I/O start, I/O completion, I/O
        // merge, or read of these stats by the number of I/Os in progress
        // (field queued_ios) times the number of milliseconds spent doing I/O since the
        // last update of this field.  This can provide an easy measure of both
        // I/O completion time and the backlog that may be accumulating.
        backlog_ms      = strtoull(procfile_lineword(ff, l, 13), NULL, 10); // rq_ticks


        // --------------------------------------------------------------------------
        // remove slashes from disk names
        char *s;
        for(s = disk; *s ;s++)
            if(*s == '/') *s = '_';

        // --------------------------------------------------------------------------
        // get a disk structure for the disk

        struct disk *d = get_disk(major, minor, disk);


        // --------------------------------------------------------------------------
        // Set its family based on mount point

        char *family = d->mount_point;
        if(!family) family = disk;


        // --------------------------------------------------------------------------
        // Check the configuration for the device

        if(unlikely(!d->configured)) {
            char var_name[4096 + 1];
            snprintfz(var_name, 4096, "plugin:proc:/proc/diskstats:%s", disk);

            int def_enable = config_get_boolean_ondemand(var_name, "enable", global_enable_new_disks_detected_at_runtime);
            if(unlikely(def_enable == CONFIG_ONDEMAND_NO)) {
                // the user does not want any metrics for this disk
                d->do_io = CONFIG_ONDEMAND_NO;
                d->do_ops = CONFIG_ONDEMAND_NO;
                d->do_mops = CONFIG_ONDEMAND_NO;
                d->do_iotime = CONFIG_ONDEMAND_NO;
                d->do_qops = CONFIG_ONDEMAND_NO;
                d->do_util = CONFIG_ONDEMAND_NO;
                d->do_backlog = CONFIG_ONDEMAND_NO;
            }
            else {
                // this disk is enabled
                // check its direct settings

                int def_performance = CONFIG_ONDEMAND_ONDEMAND;

                // since this is 'on demand' we can figure the performance settings
                // based on the type of disk

                switch(d->type) {
                    case DISK_TYPE_PHYSICAL:
                        def_performance = global_enable_performance_for_physical_disks;
                        break;

                    case DISK_TYPE_PARTITION:
                        def_performance = global_enable_performance_for_partitions;
                        break;

                    case DISK_TYPE_CONTAINER:
                        def_performance = global_enable_performance_for_virtual_disks;
                        break;
                }

                // check if we have to disable performance for this disk
                if(def_performance)
                    def_performance = is_major_enabled((int)major);

                // ------------------------------------------------------------
                // now we have def_performance and def_space
                // to work further

                // def_performance
                // check the user configuration (this will also show our 'on demand' decision)
                def_performance = config_get_boolean_ondemand(var_name, "enable performance metrics", def_performance);

                int ddo_io = CONFIG_ONDEMAND_NO,
                    ddo_ops = CONFIG_ONDEMAND_NO,
                    ddo_mops = CONFIG_ONDEMAND_NO,
                    ddo_iotime = CONFIG_ONDEMAND_NO,
                    ddo_qops = CONFIG_ONDEMAND_NO,
                    ddo_util = CONFIG_ONDEMAND_NO,
                    ddo_backlog = CONFIG_ONDEMAND_NO;

                // we enable individual performance charts only when def_performance is not disabled
                if(unlikely(def_performance != CONFIG_ONDEMAND_NO)) {
                    ddo_io = global_do_io,
                    ddo_ops = global_do_ops,
                    ddo_mops = global_do_mops,
                    ddo_iotime = global_do_iotime,
                    ddo_qops = global_do_qops,
                    ddo_util = global_do_util,
                    ddo_backlog = global_do_backlog;
                }

                d->do_io      = config_get_boolean_ondemand(var_name, "bandwidth", ddo_io);
                d->do_ops     = config_get_boolean_ondemand(var_name, "operations", ddo_ops);
                d->do_mops    = config_get_boolean_ondemand(var_name, "merged operations", ddo_mops);
                d->do_iotime  = config_get_boolean_ondemand(var_name, "i/o time", ddo_iotime);
                d->do_qops    = config_get_boolean_ondemand(var_name, "queued operations", ddo_qops);
                d->do_util    = config_get_boolean_ondemand(var_name, "utilization percentage", ddo_util);
                d->do_backlog = config_get_boolean_ondemand(var_name, "backlog", ddo_backlog);
            }

            d->configured = 1;
        }

        RRDSET *st;

        // --------------------------------------------------------------------------
        // Do performance metrics

        if(d->do_io == CONFIG_ONDEMAND_YES || (d->do_io == CONFIG_ONDEMAND_ONDEMAND && (readsectors || writesectors))) {
            d->do_io = CONFIG_ONDEMAND_YES;

            st = rrdset_find_bytype(RRD_TYPE_DISK, disk);
            if(unlikely(!st)) {
                st = rrdset_create(RRD_TYPE_DISK, disk, NULL, family, "disk.io", "Disk I/O Bandwidth", "kilobytes/s", 2000, update_every, RRDSET_TYPE_AREA);

                rrddim_add(st, "reads", NULL, d->sector_size, 1024, RRDDIM_INCREMENTAL);
                rrddim_add(st, "writes", NULL, d->sector_size * -1, 1024, RRDDIM_INCREMENTAL);
            }
            else rrdset_next(st);

            last_readsectors  = rrddim_set(st, "reads", readsectors);
            last_writesectors = rrddim_set(st, "writes", writesectors);
            rrdset_done(st);
        }

        // --------------------------------------------------------------------

        if(d->do_ops == CONFIG_ONDEMAND_YES || (d->do_ops == CONFIG_ONDEMAND_ONDEMAND && (reads || writes))) {
            d->do_ops = CONFIG_ONDEMAND_YES;

            st = rrdset_find_bytype("disk_ops", disk);
            if(unlikely(!st)) {
                st = rrdset_create("disk_ops", disk, NULL, family, "disk.ops", "Disk Completed I/O Operations", "operations/s", 2001, update_every, RRDSET_TYPE_LINE);
                st->isdetail = 1;

                rrddim_add(st, "reads", NULL, 1, 1, RRDDIM_INCREMENTAL);
                rrddim_add(st, "writes", NULL, -1, 1, RRDDIM_INCREMENTAL);
            }
            else rrdset_next(st);

            last_reads  = rrddim_set(st, "reads", reads);
            last_writes = rrddim_set(st, "writes", writes);
            rrdset_done(st);
        }

        // --------------------------------------------------------------------

        if(d->do_qops == CONFIG_ONDEMAND_YES || (d->do_qops == CONFIG_ONDEMAND_ONDEMAND && queued_ios)) {
            d->do_qops = CONFIG_ONDEMAND_YES;

            st = rrdset_find_bytype("disk_qops", disk);
            if(unlikely(!st)) {
                st = rrdset_create("disk_qops", disk, NULL, family, "disk.qops", "Disk Current I/O Operations", "operations", 2002, update_every, RRDSET_TYPE_LINE);
                st->isdetail = 1;

                rrddim_add(st, "operations", NULL, 1, 1, RRDDIM_ABSOLUTE);
            }
            else rrdset_next(st);

            rrddim_set(st, "operations", queued_ios);
            rrdset_done(st);
        }

        // --------------------------------------------------------------------

        if(d->do_backlog == CONFIG_ONDEMAND_YES || (d->do_backlog == CONFIG_ONDEMAND_ONDEMAND && backlog_ms)) {
            d->do_backlog = CONFIG_ONDEMAND_YES;

            st = rrdset_find_bytype("disk_backlog", disk);
            if(unlikely(!st)) {
                st = rrdset_create("disk_backlog", disk, NULL, family, "disk.backlog", "Disk Backlog", "backlog (ms)", 2003, update_every, RRDSET_TYPE_AREA);
                st->isdetail = 1;

                rrddim_add(st, "backlog", NULL, 1, 10, RRDDIM_INCREMENTAL);
            }
            else rrdset_next(st);

            rrddim_set(st, "backlog", backlog_ms);
            rrdset_done(st);
        }

        // --------------------------------------------------------------------

        if(d->do_util == CONFIG_ONDEMAND_YES || (d->do_util == CONFIG_ONDEMAND_ONDEMAND && busy_ms)) {
            d->do_util = CONFIG_ONDEMAND_YES;

            st = rrdset_find_bytype("disk_util", disk);
            if(unlikely(!st)) {
                st = rrdset_create("disk_util", disk, NULL, family, "disk.util", "Disk Utilization Time", "% of time working", 2004, update_every, RRDSET_TYPE_AREA);
                st->isdetail = 1;

                rrddim_add(st, "utilization", NULL, 1, 10, RRDDIM_INCREMENTAL);
            }
            else rrdset_next(st);

            last_busy_ms = rrddim_set(st, "utilization", busy_ms);
            rrdset_done(st);
        }

        // --------------------------------------------------------------------

        if(d->do_mops == CONFIG_ONDEMAND_YES || (d->do_mops == CONFIG_ONDEMAND_ONDEMAND && (mreads || mwrites))) {
            d->do_mops = CONFIG_ONDEMAND_YES;

            st = rrdset_find_bytype("disk_mops", disk);
            if(unlikely(!st)) {
                st = rrdset_create("disk_mops", disk, NULL, family, "disk.mops", "Disk Merged Operations", "merged operations/s", 2021, update_every, RRDSET_TYPE_LINE);
                st->isdetail = 1;

                rrddim_add(st, "reads", NULL, 1, 1, RRDDIM_INCREMENTAL);
                rrddim_add(st, "writes", NULL, -1, 1, RRDDIM_INCREMENTAL);
            }
            else rrdset_next(st);

            rrddim_set(st, "reads", mreads);
            rrddim_set(st, "writes", mwrites);
            rrdset_done(st);
        }

        // --------------------------------------------------------------------

        if(d->do_iotime == CONFIG_ONDEMAND_YES || (d->do_iotime == CONFIG_ONDEMAND_ONDEMAND && (readms || writems))) {
            d->do_iotime = CONFIG_ONDEMAND_YES;

            st = rrdset_find_bytype("disk_iotime", disk);
            if(unlikely(!st)) {
                st = rrdset_create("disk_iotime", disk, NULL, family, "disk.iotime", "Disk Total I/O Time", "milliseconds/s", 2022, update_every, RRDSET_TYPE_LINE);
                st->isdetail = 1;

                rrddim_add(st, "reads", NULL, 1, 1, RRDDIM_INCREMENTAL);
                rrddim_add(st, "writes", NULL, -1, 1, RRDDIM_INCREMENTAL);
            }
            else rrdset_next(st);

            last_readms  = rrddim_set(st, "reads", readms);
            last_writems = rrddim_set(st, "writes", writems);
            rrdset_done(st);
        }

        // --------------------------------------------------------------------
        // calculate differential charts
        // only if this is not the first time we run

        if(likely(dt)) {
            if( (d->do_iotime == CONFIG_ONDEMAND_YES || (d->do_iotime == CONFIG_ONDEMAND_ONDEMAND && (readms || writems))) &&
                (d->do_ops    == CONFIG_ONDEMAND_YES || (d->do_ops    == CONFIG_ONDEMAND_ONDEMAND && (reads || writes)))) {
                st = rrdset_find_bytype("disk_await", disk);
                if(unlikely(!st)) {
                    st = rrdset_create("disk_await", disk, NULL, family, "disk.await", "Average Completed I/O Operation Time", "ms per operation", 2005, update_every, RRDSET_TYPE_LINE);
                    st->isdetail = 1;

                    rrddim_add(st, "reads", NULL, 1, 1, RRDDIM_ABSOLUTE);
                    rrddim_add(st, "writes", NULL, -1, 1, RRDDIM_ABSOLUTE);
                }
                else rrdset_next(st);

                rrddim_set(st, "reads", (reads - last_reads) ? (readms - last_readms) / (reads - last_reads) : 0);
                rrddim_set(st, "writes", (writes - last_writes) ? (writems - last_writems) / (writes - last_writes) : 0);
                rrdset_done(st);
            }

            if( (d->do_io  == CONFIG_ONDEMAND_YES || (d->do_io  == CONFIG_ONDEMAND_ONDEMAND && (readsectors || writesectors))) &&
                (d->do_ops == CONFIG_ONDEMAND_YES || (d->do_ops == CONFIG_ONDEMAND_ONDEMAND && (reads || writes)))) {
                st = rrdset_find_bytype("disk_avgsz", disk);
                if(unlikely(!st)) {
                    st = rrdset_create("disk_avgsz", disk, NULL, family, "disk.avgsz", "Average Completed I/O Operation Bandwidth", "kilobytes per operation", 2006, update_every, RRDSET_TYPE_AREA);
                    st->isdetail = 1;

                    rrddim_add(st, "reads", NULL, d->sector_size, 1024, RRDDIM_ABSOLUTE);
                    rrddim_add(st, "writes", NULL, d->sector_size * -1, 1024, RRDDIM_ABSOLUTE);
                }
                else rrdset_next(st);

                rrddim_set(st, "reads", (reads - last_reads) ? (readsectors - last_readsectors) / (reads - last_reads) : 0);
                rrddim_set(st, "writes", (writes - last_writes) ? (writesectors - last_writesectors) / (writes - last_writes) : 0);
                rrdset_done(st);
            }

            if( (d->do_util == CONFIG_ONDEMAND_YES || (d->do_util == CONFIG_ONDEMAND_ONDEMAND && busy_ms)) &&
                (d->do_ops  == CONFIG_ONDEMAND_YES || (d->do_ops  == CONFIG_ONDEMAND_ONDEMAND && (reads || writes)))) {
                st = rrdset_find_bytype("disk_svctm", disk);
                if(unlikely(!st)) {
                    st = rrdset_create("disk_svctm", disk, NULL, family, "disk.svctm", "Average Service Time", "ms per operation", 2007, update_every, RRDSET_TYPE_LINE);
                    st->isdetail = 1;

                    rrddim_add(st, "svctm", NULL, 1, 1, RRDDIM_ABSOLUTE);
                }
                else rrdset_next(st);

                rrddim_set(st, "svctm", ((reads - last_reads) + (writes - last_writes)) ? (busy_ms - last_busy_ms) / ((reads - last_reads) + (writes - last_writes)) : 0);
                rrdset_done(st);
            }
        }
    }

    return 0;
}
